D. L. Ballard, P. L. Martin, Air Force Research Laboratory, Wright-Patterson AFB, OH; B. Gleeson, University of Pittsburgh, Pittsburgh, PA; S. Menon, Universal Energy Systems, Wright-Patterson AFB, OH
Chromium and hafnium have long been seen as beneficial elemental additions to Nickel-base superalloys for oxidation resistance and scale adhesion. This will be shown to be particularly true for model Pt-modified γ+γ′ (Ni+Ni3Al) alloys. However, results also indicate that increasing chromium concentration can also be deleterious to bulk alloy melting temperatures and higher hafnium contents cause significant increases in internal oxidation. Data will be presented showing the differences in melting temperature ranges for PGM-modified γ+γ′ alloys with 0-10 at.% Cr and oxidation differences with 0.1-0.5 at.% Hf additions. These effects will be described and related to their impact on attaining chemical homogeneity in cast buttons.
Summary: The effects of varying chromium and hafnium concentrations on the liquidus temperature and internal oxidation behavior of platinum group metal modified nickel base alloys will be discussed.
